U.S. patent number 10,138,362 [Application Number 15/311,391] was granted by the patent office on 2018-11-27 for ethylene-based polymer composition for films with improved toughness.
This patent grant is currently assigned to Dow Global Technologies LLC. The grantee listed for this patent is Dow Global Technologies LLC. Invention is credited to Anthony J. Castelluccio, Mehmet Demirors, Douglas S. Ginger, Pradeep Jain, Mridula Kapur, Jian Wang.
United States Patent |
10,138,362 |
Wang , et al. |
November 27, 2018 |
Ethylene-based polymer composition for films with improved
toughness
Abstract
The invention provides a composition comprising a first
composition, comprising at least one ethylene-based polymer, and
wherein the first composition comprises a MWCDI value greater than
0.9, and a melt index ratio I10/I2 that meets the following
equation: I10/I2.gtoreq.7.0-1.2.times.log (I2). The invention also
provides a process to form a composition comprising at least two
ethylene-based polymers, said process comprising the following:
polymerizing ethylene, and optionally at least one comonomer, in
solution, in the presence of a catalyst system comprising a
metal-ligand complex of Structure I, as described herein, to form a
first ethylene-based polymer; and polymerizing ethylene, and
optionally at least one comonomer, in the presence of a catalyst
system comprising a Ziegler/Natta catalyst, to form a second
ethylene-based polymer.
Inventors: |
Wang; Jian (Freeport, TX),
Jain; Pradeep (Lake Jackson, TX), Demirors; Mehmet
(Freeport, TX), Ginger; Douglas S. (Freeport, TX),
Castelluccio; Anthony J. (Lake Jackson, TX), Kapur;
Mridula (Lake Jackson, TX) |
Applicant: |
Name |
City |
State |
Country |
Type |
Dow Global Technologies LLC |
Midland |
MI |
US |
|
|
Assignee: |
Dow Global Technologies LLC
(Midland, MI)
|
Family
ID: |
53514431 |
Appl.
No.: |
15/311,391 |
Filed: |
June 26, 2015 |
PCT
Filed: |
June 26, 2015 |
PCT No.: |
PCT/US2015/037869 |
371(c)(1),(2),(4) Date: |
November 15, 2016 |
PCT
Pub. No.: |
WO2015/200740 |
PCT
Pub. Date: |
December 30, 2015 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170081444 A1 |
Mar 23, 2017 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62017525 |
Jun 26, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B
27/06 (20130101); B32B 27/28 (20130101); C08L
23/0807 (20130101); B32B 5/022 (20130101); B32B
7/00 (20130101); B32B 27/18 (20130101); B32B
27/308 (20130101); B32B 27/30 (20130101); E01C
13/08 (20130101); B32B 7/02 (20130101); B32B
27/12 (20130101); B32B 27/32 (20130101); A61F
13/51401 (20130101); B32B 27/306 (20130101); B32B
27/08 (20130101); C08J 5/00 (20130101); C08L
23/0815 (20130101); B32B 5/02 (20130101); C08F
210/16 (20130101); B32B 27/325 (20130101); A61F
13/51458 (20130101); B32B 27/20 (20130101); B32B
5/00 (20130101); C08J 5/18 (20130101); C08K
3/26 (20130101); C08F 210/16 (20130101); C08F
4/64193 (20130101); C08F 4/6555 (20130101); C08F
210/16 (20130101); C08F 2/06 (20130101); C08L
23/0815 (20130101); C08L 2314/02 (20130101); C08L
2314/06 (20130101); C08L 23/0807 (20130101); C08L
2314/02 (20130101); C08L 2314/06 (20130101); B32B
2262/0253 (20130101); B32B 2307/544 (20130101); C08J
2423/08 (20130101); C08L 2314/06 (20130101); B32B
2307/724 (20130101); C08F 2500/11 (20130101); C08J
2323/06 (20130101); B32B 2255/02 (20130101); C08K
2003/265 (20130101); A61F 2013/51409 (20130101); B32B
2270/00 (20130101); C08J 2323/08 (20130101); B32B
2307/50 (20130101); C08L 2205/16 (20130101); B32B
2262/00 (20130101); C08F 2500/18 (20130101); B32B
2307/718 (20130101); B32B 2307/726 (20130101); C08F
2500/12 (20130101); B32B 2307/514 (20130101); B32B
2555/00 (20130101); C08L 2203/12 (20130101); B32B
2262/02 (20130101); C08L 2205/025 (20130101); C08L
2314/02 (20130101); B32B 2255/00 (20130101); C08F
210/16 (20130101); C08F 2500/10 (20130101); C08F
2500/12 (20130101); C08F 2500/19 (20130101) |
Current International
Class: |
C08F
210/16 (20060101); C08J 5/00 (20060101); C08K
3/26 (20060101); B32B 27/12 (20060101); B32B
27/08 (20060101); A61F 13/514 (20060101); C08J
5/18 (20060101); B32B 27/32 (20060101); B32B
27/30 (20060101); B32B 27/28 (20060101); B32B
27/20 (20060101); B32B 27/18 (20060101); B32B
27/06 (20060101); B32B 7/02 (20060101); B32B
7/00 (20060101); B32B 5/02 (20060101); B32B
5/00 (20060101); E01C 13/08 (20060101); C08L
23/08 (20060101) |
References Cited
[Referenced By]
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Foreign Patent Documents
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98/21274 |
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May 1998 |
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WO |
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WO |
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1998021274 |
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May 1998 |
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WO |
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98/26000 |
|
Jun 1998 |
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WO |
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2012/134700 |
|
Oct 2012 |
|
WO |
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2012134700 |
|
Oct 2012 |
|
WO |
|
2014/058639 |
|
Apr 2014 |
|
WO |
|
2014/058639 |
|
Apr 2014 |
|
WO |
|
2015/198138 |
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Dec 2015 |
|
WO |
|
2015200741 |
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Dec 2015 |
|
WO |
|
2015200742 |
|
Dec 2015 |
|
WO |
|
2015200743 |
|
Dec 2015 |
|
WO |
|
Other References
Karjala et al., Detection of Low Levels of Long-Chain Branching in
Polyolefins, Antec, 2008, pp. 887-891. cited by applicant .
Monrabel et al, Crystallization Elution Fractionation and Thermal
Gradient Interaction Chromatography Techniques Comparison,
Macromol, Symp., 2012, vol. 312, pp. 115-139. cited by applicant
.
PCT/US2015/037869; International Search Report & Written
Opinion dated Dec. 14, 2015. cited by applicant .
PCT/US2015/037869; International Preliminary Report on
Patentability dated Sep. 15, 2016. cited by applicant .
PCT/US2015/037869; Third Party Submission dated Apr. 15, 2016.
cited by applicant .
PCT/US2015/037869; Third Party Submission Summary dated Apr. 15,
2016. cited by applicant .
Karjala et al., "Detection of Low Levels of Long-Chain Branching in
Polyolefins", ANTEC, (2008), pp. 887-891. cited by third party
.
Monrabal et al., "Crystallization Elution Fractionation and Thermal
Gradient Interaction Chromatography. Techniques Comparison",
Macromol. Symp., vol. 312, (2012), pp. 115-129. cited by third
party.
|
Primary Examiner: Nutter; Nathan M
Parent Case Text
REFERENCE TO RELATED APPLICATIONS
The present application claims the benefit of U.S. Provisional
Application No. 62/017,525, filed Jun. 26, 2014, and incorporated
herein by reference.
Claims
The invention claimed is:
1. A composition comprising a first composition, comprising at
least one ethylene-based polymer, and wherein the first composition
comprises a MWCDI value greater than 1.2, and a melt index ratio
(I10/I2) that meets the following equation:
I10/I2.gtoreq.7.0-1.2.times.log (I2).
2. The composition of claim 1, wherein the first composition has a
MWCDI value less than, or equal to, 10.0.
3. The composition of claim 1, wherein the ethylene-based polymer
is an ethylene/.alpha.-olefin interpolymer.
4. The composition of claim 1, wherein the first composition
further comprises a second ethylene-based polymer.
5. The composition of claim 4, wherein the second ethylene-based
polymer is an ethylene/.alpha.-olefin interpolymer.
6. The composition of claim 1, wherein the first composition has a
ZSVR value from 1.2 to 3.0.
7. The composition of claim 1, wherein the first composition has a
melt index ratio I10/I2 less than, or equal to, 9.2.
8. The composition of claim 1, wherein the first composition has a
vinyl unsaturation level greater than 10 vinyls per 1,000,000 total
carbons.
9. The composition of claim 1, wherein the composition further
comprises another polymer.
10. The composition of claim 9, wherein the polymer is selected
from the following: a LLDPE, a LDPE, a HDPE, a propylene-based
polymer, or a combination thereof.
11. An article comprising at least one component formed from the
composition of claim 1.
12. The article of claim 11, wherein the article is a film or
coating.
Description
BACKGROUND OF THE INVENTION
Various polymerization techniques, using different catalyst
systems, have been employed to produce ethylene-based polymer
compositions suitable for films. Ethylene-based polymer
compositions are described in the following references: U.S. Pat.
No. 5,844,045 (see also U.S. Pat. No. 5,869,575 and U.S. Pat. No.
6,448,341), U.S. Pat. No. 6,566,446, U.S. Pat. No. 5,677,383 (see
also U.S. Pat. No. 6,111,023), U.S. Pat. No. 5,977,251,
US2015/0148490, US2015/0148491 and WO2014/058639. However, there
remains a need for compositions that can be used to form films with
improved toughness, while maintaining a good balance of other film
physical properties, such as MD tear, puncture, and optics. These
needs have been met by the following invention.
SUMMARY OF THE INVENTION
The instant invention provides a composition comprising a first
composition, comprising at least one ethylene-based polymer, and
wherein the first composition comprises a MWCDI value greater than
0.9, and a melt index ratio (I10/I2) that meets the following
equation: I10/I2.gtoreq.7.0-1.2.times.log (I2).
The invention also provides a process to form a composition
comprising at least two ethylene-based polymers, said process
comprising the following:
polymerizing ethylene, and optionally at least one comonomer, in
solution, in the presence of a catalyst system comprising a
metal-ligand complex of Structure I, to form a first ethylene-based
polymer; and
polymerizing ethylene, and optionally at least one comonomer, in
the presence of a catalyst system comprising a Ziegler/Natta
catalyst, to form a second ethylene-based polymer; and
wherein Structure I is as follows:
##STR00001## wherein:
M is titanium, zirconium, or hafnium, each independently being in a
formal oxidation state of +2, +3, or +4; and
n is an integer from 0 to 3, and wherein when n is 0, X is absent;
and
each X independently is a monodentate ligand that is neutral,
monoanionic, or dianionic; or two Xs are taken together to form a
bidentate ligand that is neutral, monoanionic, or dianionic;
and
X and n are chosen, in such a way, that the metal-ligand complex of
formula (I) is, overall neutral; and
each Z independently is O, S, N(C.sub.1-C.sub.40)hydrocarbyl, or
P(C.sub.1-C.sub.40)hydrocarbyl; and
wherein the Z-L-Z fragment is comprised of formula (1):
##STR00002##
R.sup.1 through R.sup.16 are each, independently, selected from the
group consisting of the following: a substituted or unsubstituted
(C.sub.1-C.sub.40)hydrocarbyl, a substituted or unsubstituted
(C.sub.1-C.sub.40)heterohydrocarbyl, Si(R.sup.C).sub.3,
Ge(R.sup.C).sub.3, P(R.sup.P).sub.2, N(R.sup.N).sub.2, OR.sup.C,
SR.sup.C, NO.sub.2, CN, CF.sub.3, R.sup.CS(O)--,
R.sup.CS(O).sub.2--, (R.sup.C).sub.2C.dbd.N--, R.sup.CC(O)O--,
R.sup.COC(O)--, R.sup.CC(O)N(R)--, (R.sup.C).sub.2NC(O)--, halogen
atom, hydrogen atom; and wherein each R.sup.C is independently a
(C1-C30)hydrocarbyl; R.sup.P is a (C1-C30)hydrocarbyl; and R.sup.N
is a (C1-C30)hydrocarbyl; and
wherein, optionally, two or more R groups (from R.sup.1 through
R.sup.16) can combine together into one or more ring structures,
with such ring structures each, independently, having from 3 to 50
atoms in the ring, excluding any hydrogen atom.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts the plot of "SCB.sub.f versus IR5 Area Ratio" for
ten SCB Standards.
FIG. 2 depicts the several GPC profiles for the determination of
IR5 Height Ratio for Inventive First Composition 2.
FIG. 3 depicts the plot of "SCB.sub.f versus Polyethylene
Equivalent molecular Log Mw.sub.i (GPC)" for Inventive First
Composition 2.
FIG. 4 depicts a plot of the "Mole Percent Comonomer versus
Polyethylene Equivalent Log.sub.Mwi (GPC)" for Inventive First
Composition 2.
FIG. 5 depicts some GPC MWD profiles and corresponding comonomer
distribution overlays for some inventive and comparative
compositions (density 0.916-0.919 g/cc).
FIG. 6 depicts some GPC MWD profiles and corresponding comonomer
distribution overlays for some inventive and comparative
compositions (density 0.924-0.926 g/cc).
FIG. 7 depicts some GPC MWD profiles and corresponding comonomer
distribution overlays for some inventive and comparative
compositions (Cast stretch).
DETAILED DESCRIPTION OF THE INVENTION
It has been discovered that the inventive compositions can be used
to form films with improved toughness. Such compositions contain an
ethylene-based polymer that has a superior comonomer distribution,
which is significantly higher in comonomer concentration, and a
good distribution of comonomer, in the high molecular weight
polymer molecules, and is significantly lower in comonomer
concentration in the low molecular weight polymer molecules, as
compared to conventional polymers of the art at the same overall
density. It has also been discovered that the ethylene-based
polymer has low LCB (Long Chain Branches), as indicated by low
ZSVR, as compared to conventional polymers. As the result of this
optimized distribution of the comonomer, as well as the inherent
low LCB nature, the inventive compositions have more tie chains,
and thus, improved film toughness.
As discussed above, the invention provides a composition comprising
a first composition, comprising at least one ethylene-based
polymer, and wherein the first composition comprises a MWCDI value
greater than 0.9, and a melt index ratio (I10/I2) that meets the
following equation: I10/I2.gtoreq.7.0-1.2.times.log (I2).
The inventive composition may comprise a combination of two or more
embodiments described herein.
The first composition may comprise a combination of two or more
embodiments as described herein.
The ethylene-based polymer may comprise a combination of two or
more embodiments as described herein.
In one embodiment, the first composition has a MWCDI value less
than, or equal to, 10.0, further less than, or equal to, 8.0,
further less than, or equal to, 6.0.
In one embodiment, the first composition has a MWCDI value less
than, or equal to, 5.0, further less than, or equal to, 4.0,
further less than, or equal to, 3.0.
In one embodiment, the first composition has a MWCDI value greater
than, or equal to, 1.0, further greater than, or equal to, 1.1,
further greater than, or equal to, 1.2.
In one embodiment, the first composition has a MWCDI value greater
than, or equal to, 1.3, further greater than, or equal to, 1.4,
further greater than, or equal to, 1.5.
In one embodiment, the first composition has a melt index ratio
I10/I2 greater than, or equal to, 7.0, further greater than, or
equal to, 7.1, further greater than, or equal to, 7.2, further
greater than, or equal to, 7.3.
In one embodiment, the first composition has a melt index ratio
I10/I2 less than, or equal to, 9.2, further less than, or equal to,
9.0, further less than, or equal to, 8.8, further less than, or
equal to, 8.5.
In one embodiment, the first composition has a ZSVR value from 1.2
to 3.0, further from 1.2 to 2.5, further 1.2 to 2.0.
In one embodiment, the first composition has a vinyl unsaturation
level greater than 10 vinyls per 1,000,000 total carbons. For
example, greater than 20 vinyls per 1,000,000 total carbons, or
greater than 50 vinyls per 1,000,000 total carbons, or greater than
70 vinyls per 1,000,000 total carbons, or greater than 100 vinyls
per 1,000,000 total carbons.
In one embodiment, the first composition has a density in the range
of 0.910 to 0.940 g/cm.sup.3, for example from 0.910 to 0.930, or
from 0.910 to 0.925 g/cm.sup.3. For example, the density can be
from a lower limit of 0.910, 0.912, or 0.914 g/cm.sup.3, to an
upper limit of 0.925, 0.927, or 0.930 g/cm.sup.3 (1 cm.sup.3=1
cc).
In one embodiment, the first composition has a melt index (I.sub.2
or I2; at 190.degree. C./2.16 kg) from 0.1 to 50 g/10 minutes, for
example from 0.1 to 30 g/10 minutes, or from 0.1 to 20 g/10
minutes, or from 0.1 to 10 g/10 minutes. For example, the melt
index (I.sub.2 or I2; at 190.degree. C./2.16 kg) can be from a
lower limit of 0.1, 0.2, or 0.5 g/10 minutes, to an upper limit of
1.0, 2.0, 3.0, 4.0, 5.0, 10, 15, 20, 25, 30, 40, or 50 g/10
minutes.
In one embodiment, the first composition has a molecular weight
distribution, expressed as the ratio of the weight average
molecular weight to number average molecular weight
(M.sub.w/M.sub.n; as determined by cony. GPC) in the range of from
2.2 to 5.0. For example, the molecular weight distribution
(M.sub.w/M.sub.n) can be from a lower limit of 2.2, 2.3, 2.4, 2.5,
3.0, 3.2, or 3.4, to an upper limit of 3.9, 4.0, 4.1, 4.2, 4.5,
5.0.
In one embodiment, the first composition has a number average
molecular weight (M.sub.n; as determined by cony. GPC) in the range
from 10,000 to 50,000 g/mole. For example, the number average
molecular weight can be from a lower limit of 10,000, 20,000, or
25,000 g/mole, to an upper limit of 35,000, 40,000, 45,000, or
50,000 g/mole.
In one embodiment, the first composition has a weight average
molecular weight (M.sub.w; as determined by cony. GPC) in the range
from 70,000 to 200,000 g/mole. For example, the number average
molecular weight can be from a lower limit of 70,000, 75,000, or
78,000 g/mole, to an upper limit of 120,000, 140,000, 160,000,
180,000 or 200,000 g/mole.
In one embodiment, the first composition has a melt viscosity
ratio, Eta*0.1/Eta*100, in the range from 2.2 to 7.0. For example,
the number average molecular weight can be from a lower limit of
2.2, 2.3, 2.4 or 2.5, to an upper limit of 6.0, 6.2, 6.5, or
7.0.
In one embodiment, the ethylene-based polymer is an
ethylene/.alpha.-olefin interpolymer, and further an
ethylene/.alpha.-olefin copolymer.
In one embodiment, the first ethylene-based polymer is an
ethylene/.alpha.-olefin interpolymer, and further an
ethylene/.alpha.-olefin copolymer.
In one embodiment, the .alpha.-olefin has less than, or equal to,
20 carbon atoms. For example, the .alpha.-olefin comonomers may
preferably have 3 to 10 carbon atoms, and more preferably 3 to 8
carbon atoms. Exemplary .alpha.-olefin comonomers include, but are
not limited to, propylene, 1-butene, 1-pentene, 1-hexene,
1-heptene, 1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene.
The one or more .alpha.-olefin comonomers may, for example, be
selected from the group consisting of propylene, 1-butene,
1-hexene, and 1-octene; or in the alternative, from the group
consisting of 1-butene, 1-hexene and 1-octene, and further 1-hexene
and 1-octene.
In one embodiment, the ethylene-based polymer, or first
ethylene-based polymer, has a molecular weight distribution
(M.sub.w/M.sub.n; as determined by cony. GPC) in the range from 1.5
to 4.0, for example, from 1.5 to 3.5, or from 2.0 to 3.0. For
example, the molecular weight distribution (M.sub.w/M.sub.n) can be
from a lower limit of 1.5, 1.7, 2.0, 2.1, or 2.2, to an upper limit
of 2.5, 2.6, 2.8, 3.0, 3.5 or 4.0.
In one embodiment, the first composition further comprises a second
ethylene-based polymer. In a further embodiment, the second
ethylene-based polymer is an ethylene/.alpha.-olefin interpolymer,
and further an ethylene/.alpha.-olefin copolymer.
In one embodiment, the .alpha.-olefin has less than, or equal to,
20 carbon atoms. For example, the .alpha.-olefin comonomers may
preferably have 3 to 10 carbon atoms, and more preferably 3 to 8
carbon atoms. Exemplary .alpha.-olefin comonomers include, but are
not limited to, propylene, 1-butene, 1-pentene, 1-hexene,
1-heptene, 1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene.
The one or more .alpha.-olefin comonomers may, for example, be
selected from the group consisting of propylene, 1-butene,
1-hexene, and 1-octene; or in the alternative, from the group
consisting of 1-butene, 1-hexene and 1-octene, and further 1-hexene
and 1-octene.
In one embodiment, the second ethylene-based polymer is a
heterogeneously branched ethylene/.alpha.-olefin interpolymer, and
further a heterogeneously branched ethylene/.alpha.-olefin
copolymer. Heterogeneously branched ethylene/.alpha.-olefin
interpolymers and copolymers are typically produced using
Ziegler/Natta type catalyst system, and have more comonomer
distributed in the lower molecular weight molecules of the
polymer.
In one embodiment, the second ethylene-based polymer has a
molecular weight distribution (M.sub.w/M.sub.n) in the range from
3.0 to 5.0, for example from 3.2 to 4.6. For example, the molecular
weight distribution (M.sub.w/M.sub.n) can be from a lower limit of
3.2, 3.3, 3.5, 3.7, or 3.9, to an upper limit of 4.6, 4.7, 4.8,
4.9, or 5.0.
In one embodiment, the composition comprises from 50 to 80 wt %, or
from 50 to 85 wt %, or from 50 to 90 wt %, or from 50 to 95 wt % of
the first composition, based on the weight of the composition.
In one embodiment, the composition comprises greater than, or equal
to, 80 wt %, or greater than, or equal to, 85 wt %, or greater
than, or equal to, 90 wt %, or greater than, or equal to, 95 wt %,
or greater than, or equal to 98 wt % of the first composition,
based on the weight of the composition.
In one embodiment, the composition further comprises another
polymer. In a further embodiment, the polymer is selected from the
following: a LLDPE, a MDPE, a LDPE, a HDPE, a propylene-based
polymer, or a combination thereof.
In one embodiment, the composition further comprises a LDPE. In a
further embodiment, the LDPE is present in an amount from 5 to 50
wt %, further from 10 to 40 wt %, further from 15 to 30 wt %, based
on the weight of the composition. In a further embodiment, the LDPE
has a density from 0.915 to 0.925 g/cc, and a melt index (I2) from
0.5 to 5 g/10 min, further from 1.0 to 3.0 g/10 min.
In one embodiment, the composition further comprises one or more
additives. The invention also provides an article comprising at
least one component formed from an inventive composition as
described herein. In a further embodiment, the article is a film or
a coating.
Polymerization
Polymerization processes include, but are not limited to, solution
polymerization processes, using one or more conventional reactors,
e.g., loop reactors, isothermal reactors, adiabatic reactors,
stirred tank reactors, autoclave reactors in parallel, series,
and/or any combinations thereof. The ethylene based polymer
compositions may, for example, be produced via solution phase
polymerization processes, using one or more loop reactors,
adiabatic reactors, and combinations thereof.
In general, the solution phase polymerization process occurs in one
or more well mixed reactors, such as one or more loop reactors
and/or one or more adiabatic reactors at a temperature in the range
from 115 to 250.degree. C.; for example, from 135 to 200.degree.
C., and at pressures in the range of from 300 to 1000 psig, for
example, from 450 to 750 psig.
In one embodiment, the ethylene based polymer composition (e.g.,
the first composition of claim 1) may be produced in two loop
reactors in series configuration, the first reactor temperature is
in the range from 115 to 200.degree. C., for example, from 135 to
165.degree. C., and the second reactor temperature is in the range
from 150 to 210.degree. C., for example, from 185 to 200.degree. C.
In another embodiment, the ethylene based polymer composition may
be produced in a single reactor, the reactor temperature is in the
range from 115 to 200.degree. C., for example from 130 to
190.degree. C. The residence time in a solution phase
polymerization process is typically in the range from 2 to 40
minutes, for example from 5 to 20 minutes. Ethylene, solvent, one
or more catalyst systems, optionally one or more cocatalysts, and
optionally one or more comonomers, are fed continuously to one or
more reactors. Exemplary solvents include, but are not limited to,
isoparaffins. For example, such solvents are commercially available
under the name ISOPAR E from ExxonMobil Chemical. The resultant
mixture of the ethylene based polymer composition and solvent is
then removed from the reactor or reactors, and the ethylene based
polymer composition is isolated. Solvent is typically recovered via
a solvent recovery unit, i.e., heat exchangers and separator
vessel, and the solvent is then recycled back into the
polymerization system.
In one embodiment, the ethylene based polymer composition may be
produced, via a solution polymerization process, in a dual reactor
system, for example a dual loop reactor system, wherein ethylene,
and optionally one or more .alpha.-olefins, are polymerized in the
presence of one or more catalyst systems, in one reactor, to
produce a first ethylene-based polymer, and ethylene, and
optionally one or more .alpha.-olefins, are polymerized in the
presence of one or more catalyst systems, in a second reactor, to
produce a second ethylene-based polymer. Additionally, one or more
cocatalysts may be present.
In another embodiment, the ethylene based polymer composition may
be produced via a solution polymerization process, in a single
reactor system, for example, a single loop reactor system, wherein
ethylene, and optionally one or more .alpha.-olefins, are
polymerized in the presence of one or more catalyst systems.
Additionally, one or more cocatalysts may be present.
As discussed above, the invention provides a process to form a
composition comprising at least two ethylene-based polymers, said
process comprising the following:
polymerizing ethylene, and optionally at least one comonomer, in
solution, in the present of a catalyst system comprising a
metal-ligand complex of Structure I, to form a first ethylene-based
polymer; and
polymerizing ethylene, and optionally at least one comonomer, in
the presence of a catalyst system comprising a Ziegler/Natta
catalyst, to form a second ethylene-based polymer; and
wherein Structure I is as follows:
##STR00003## wherein:
M is titanium, zirconium, or hafnium, each, independently, being in
a formal oxidation state of +2, +3, or +4; and
n is an integer from 0 to 3, and wherein when n is 0, X is absent;
and
each X, independently, is a monodentate ligand that is neutral,
monoanionic, or dianionic; or two Xs are taken together to form a
bidentate ligand that is neutral, monoanionic, or dianionic;
and
X and n are chosen, in such a way, that the metal-ligand complex of
formula (I) is, overall, neutral; and
each Z, independently, is O, S, N(C.sub.1-C.sub.40)hydrocarbyl, or
P(C.sub.1-C.sub.40)hydrocarbyl; and
wherein the Z-L-Z fragment is comprised of formula (1):
##STR00004##
R.sup.1 through R.sup.16 are each, independently, selected from the
group consisting of the following: a substituted or unsubstituted
(C.sub.1-C.sub.40)hydrocarbyl, a substituted or unsubstituted
(C.sub.1-C.sub.40)heterohydrocarbyl, Si(R.sup.C).sub.3,
Ge(R.sup.C).sub.3, P(R.sup.P).sub.2, N(R.sup.N).sub.2, OR.sup.C,
SR.sup.C, NO.sub.2, CN, CF.sub.3, R.sup.CS(O)--,
R.sup.CS(O).sub.2--, (R.sup.C).sub.2C.dbd.N--, R.sup.CC(O)O--,
R.sup.COC(O)--, R.sup.CC(O)N(R)--, (R.sup.C).sub.2NC(O)--, halogen
atom, hydrogen atom; and wherein each R.sup.C is independently a
(C1-C30)hydrocarbyl; R.sup.P is a (C1-C30)hydrocarbyl; and R.sup.N
is a (C1-C30)hydrocarbyl; and
wherein, optionally, two or more R groups (from R.sup.1 through
R.sup.16) can combine together into one or more ring structures,
with such ring structures each, independently, having from 3 to 50
atoms in the ring, excluding any hydrogen atom.
An inventive process may comprise a combination of two or more
embodiments as described herein.
In one embodiment, said process comprises polymerizing ethylene,
and optionally at least one .alpha.-olefin, in solution, in the
presence of a catalyst system comprising a metal-ligand complex of
Structure I, to form a first ethylene-based polymer; and
polymerizing ethylene, and optionally at least one .alpha.-olefin,
in the presence of a catalyst system comprising a Ziegler/Natta
catalyst, to form a second ethylene-based polymer. In a further
embodiment, each .alpha.-olefin is independently a C1-C8
.alpha.-olefin.
In one embodiment, optionally, two or more R groups from R.sup.9
through R.sup.13, or R.sup.4 through R.sup.8 can combine together
into one or more ring structures, with such ring structures each,
independently, having from 3 to 50 atoms in the ring, excluding any
hydrogen atom.
In one embodiment, M is hafnium.
In one embodiment, R.sup.3 and R.sup.14 are each independently an
alkyl, and further a C1-C3 alkyl, and further methyl.
In one embodiment, R.sup.1 and R.sup.16 are each as follows:
##STR00005##
In one embodiment, each of the aryl, heteroaryl, hydrocarbyl,
heterohydrocarbyl, Si(R.sup.C).sub.3, Ge(R.sup.C).sub.3,
P(R.sup.P).sub.2, N(R.sup.N).sub.2, OR.sup.C, SR.sup.C,
R.sup.CS(O)--, R.sup.CS(O).sub.2--, (R.sup.C).sub.2C.dbd.N--,
R.sup.CC(O)O--, R.sup.COC(O)--, R.sup.CC(O)N(R)--,
(R.sup.C).sub.2NC(O)--, hydrocarbylene, and heterohydrocarbylene
groups, independently, is unsubstituted or substituted with one or
more R.sup.S substituents; and each R.sup.S independently is a
halogen atom, polyfluoro substitution, perfluoro substitution,
unsubstituted (C.sub.1-C.sub.18)alkyl, F.sub.3C--, FCH.sub.2O--,
F.sub.2HCO--, F.sub.3CO--, R.sub.3Si--, R.sub.3Ge--, RO--, RS--,
RS(O)--, RS(O).sub.2--, R.sub.2P--, R.sub.2N--, R.sub.2C.dbd.N--,
NC--, RC(O)O--, ROC(O)--, RC(O)N(R)--, or R.sub.2NC(O)--, or two of
the R.sup.S are taken together to form an unsubstituted
(C.sub.1-C.sub.18)alkylene, wherein each R independently is an
unsubstituted (C.sub.1-C.sub.18)alkyl.
In one embodiment, two or more of R.sup.1 through R.sup.16 do not
combine to form one or more ring structures.
In one embodiment, the catalyst system suitable for producing the
first ethylene/.alpha.-olefin interpolymer is a catalyst system
comprising
bis((2-oxoyl-3-(dibenzo-1H-pyrrole-1-yl)-5-(methyl)phenyl)-2-phenoxymethy-
l)-methylene-1,2-cyclohexanediylhafnium (IV) dimethyl, represented
by the following Structure: IA:
##STR00006##
The Ziegler/Natta catalysts suitable for use in the invention are
typical supported, Ziegler-type catalysts, which are particularly
useful at the high polymerization temperatures of the solution
process. Examples of such compositions are those derived from
organomagnesium compounds, alkyl halides or aluminum halides or
hydrogen chloride, and a transition metal compound. Examples of
such catalysts are described in U.S. Pat. Nos. 4,612,300;
4,314,912; and 4,547,475; the teachings of which are incorporated
herein by reference.
Particularly suitable organomagnesium compounds include, for
example, hydrocarbon soluble dihydrocarbylmagnesium, such as the
magnesium dialkyls and the magnesium diaryls. Exemplary suitable
magnesium dialkyls include, particularly,
n-butyl-sec-butylmagnesium, diisopropylmagnesium,
di-n-hexylmagnesium, isopropyl-n-butylmagnesium,
ethyl-n-hexyl-magnesium, ethyl-n-butylmagnesium,
di-n-octylmagnesium, and others, wherein the alkyl has from 1 to 20
carbon atoms. Exemplary suitable magnesium diaryls include
diphenylmagnesium, dibenzylmagnesium and ditolylmagnesium. Suitable
organomagnesium compounds include alkyl and aryl magnesium
alkoxides and aryloxides and aryl and alkyl magnesium halides, with
the halogen-free organomagnesium compounds being more
desirable.
Halide sources include active non-metallic halides, metallic
halides, and hydrogen chloride. Suitable non-metallic halides are
represented by the formula R'X, wherein R' is hydrogen or an active
monovalent organic radical, and X is a halogen. Particularly
suitable non-metallic halides include, for example, hydrogen
halides and active organic halides, such as t-alkyl halides, allyl
halides, benzyl halides and other active hydrocarbyl halides. By an
active organic halide is meant a hydrocarbyl halide that contains a
labile halogen at least as active, i.e., as easily lost to another
compound, as the halogen of sec-butyl chloride, preferably as
active as t-butyl chloride. In addition to the organic monohalides,
it is understood that organic dihalides, trihalides and other
polyhalides that are active, as defined hereinbefore, are also
suitably employed. Examples of preferred active non-metallic
halides, include hydrogen chloride, hydrogen bromide, t-butyl
chloride, t-amyl bromide, allyl chloride, benzyl chloride, crotyl
chloride, methylvinyl carbinyl chloride, a-phenylethyl bromide,
diphenyl methyl chloride, and the like. Most preferred are hydrogen
chloride, t-butyl chloride, allyl chloride and benzyl chloride.
Suitable metallic halides include those represented by the formula
MRy-a Xa, wherein: M is a metal of Groups IIB, IIIA or IVA of
Mendeleev's periodic Table of Elements; R is a monovalent organic
radical; X is a halogen; y has a value corresponding to the valence
of M; and "a" has a value from 1 to y. Preferred metallic halides
are aluminum halides of the formula AlR.sub.3-a, X.sub.a, wherein
each R is independently hydrocarbyl, such as alkyl; X is a halogen;
and a is a number from 1 to 3. Most preferred are alkylaluminum
halides, such as ethylaluminum sesquichloride, diethylaluminum
chloride, ethylaluminum dichloride, and diethylaluminum bromide,
with ethylaluminum dichloride being especially preferred.
Alternatively, a metal halide, such as aluminum trichloride, or a
combination of aluminum trichloride with an alkyl aluminum halide,
or a trialkyl aluminum compound may be suitably employed.
Any of the conventional Ziegler-Natta transition metal compounds
can be usefully employed, as the transition metal component in
preparing the supported catalyst component. Typically, the
transition metal component is a compound of a Group IVB, VB, or VIB
metal. The transition metal component is generally, represented by
the formulas: TrX'.sub.4-q (OR1)q, TrX'.sub.4-q (R2)q, VOX'.sub.3
and VO(OR).sub.3.
Tr is a Group IVB, VB, or VIB metal, preferably a Group IVB or VB
metal, preferably titanium, vanadium or zirconium; q is 0 or a
number equal to, or less than, 4; X' is a halogen, and R1 is an
alkyl group, aryl group or cycloalkyl group having from 1 to 20
carbon atoms; and R2 is an alkyl group, aryl group, aralkyl group,
substituted aralkyls, and the like.
The aryl, aralkyls and substituted aralkys contain 1 to 20 carbon
atoms, preferably 1 to 10 carbon atoms. When the transition metal
compound contains a hydrocarbyl group, R2, being an alkyl,
cycloalkyl, aryl, or aralkyl group, the hydrocarbyl group will
preferably not contain an H atom in the position beta to the metal
carbon bond. Illustrative, but non-limiting, examples of aralkyl
groups are methyl, neopentyl, 2,2-dimethylbutyl, 2,2-dimethylhexyl;
aryl groups such as benzyl; cycloalkyl groups such as 1-norbornyl.
Mixtures of these transition metal compounds can be employed if
desired.
Illustrative examples of the transition metal compounds include
TiCl.sub.4, TiBr.sub.4, Ti(OC.sub.2H.sub.5).sub.3Cl,
Ti(OC.sub.2H.sub.5)Cl.sub.3, Ti(OC.sub.4H.sub.9).sub.3Cl,
Ti(OC.sub.3H.sub.7).sub.2Cl.sub.2,
Ti(OC.sub.6H.sub.13).sub.2Cl.sub.2,
Ti(OC.sub.8H.sub.17).sub.2Br.sub.2, and
Ti(OC.sub.12H.sub.25)Cl.sub.3, Ti(O-iC.sub.3H.sub.7).sub.4, and
Ti(O-nC.sub.4H.sub.9).sub.4. Illustrative examples of vanadium
compounds include VCl.sub.4, VOCl.sub.3, VO(OC.sub.2H.sub.5).sub.3,
and VO(OC.sub.4H.sub.9).sub.3. Illustrative examples of zirconium
compounds include ZrCl.sub.4, ZrCl.sub.3(OC.sub.2H.sub.5),
ZrCl.sub.2(OC.sub.2H.sub.5).sub.2, ZrCl(OC.sub.2H.sub.5).sub.3,
Zr(OC.sub.2H.sub.5).sub.4, ZrCl.sub.3(OC.sub.4H.sub.9),
ZrCl.sub.2(OC.sub.4H.sub.9).sub.2, and ZrCl(OC.sub.4H.sub.9)3.
An inorganic oxide support may be used in the preparation of the
catalyst, and the support may be any particulate oxide, or mixed
oxide which has been thermally or chemically dehydrated, such that
it is substantially free of adsorbed moisture. See U.S. Pat. Nos.
4,612,300; 4,314,912; and 4,547,475; the teachings of which are
incorporated herein by reference.
In one embodiment, the composition comprises a MWCDI value greater
than 0.9. In one embodiment, the composition comprises a melt index
ratio (I10/I2) that meets the following equation:
I10/I2.gtoreq.7.0-1.2.times.log (I2).
The composition may comprise one embodiment, or a combination of
two or more embodiments, as listed above for the "first
composition."
An inventive process may comprise a combination of two or more
embodiments described herein.
Co-Catalyst Component
The above described catalyst systems can be rendered catalytically
active by contacting it to, or combining it with, the activating
co-catalyst, or by using an activating technique, such as those
known in the art, for use with metal-based olefin polymerization
reactions. Suitable activating co-catalysts, for use herein,
include alkyl aluminums; polymeric or oligomeric alumoxanes (also
known as aluminoxanes); neutral Lewis acids; and non-polymeric,
non-coordinating, ion-forming compounds (including the use of such
compounds under oxidizing conditions). A suitable activating
technique is bulk electrolysis. Combinations of one or more of the
foregoing activating co-catalysts and techniques are also
contemplated. The term "alkyl aluminum" means a monoalkyl aluminum
dihydride or monoalkylaluminum dihalide, a dialkyl aluminum hydride
or dialkyl aluminum halide, or a trialkylaluminum. Aluminoxanes and
their preparations are known at, for example, U.S. Pat. No.
6,103,657. Examples of preferred polymeric or oligomeric alumoxanes
are methylalumoxane, triisobutylaluminum-modified methylalumoxane,
and isobutylalumoxane.
Exemplary Lewis acid activating co-catalysts are Group 13 metal
compounds containing from 1 to 3 hydrocarbyl substituents as
described herein. In some embodiments, exemplary Group 13 metal
compounds are tri(hydrocarbyl)-substituted-aluminum or
tri(hydrocarbyl)-boron compounds. In some other embodiments,
exemplary Group 13 metal compounds are
tri(hydrocarbyl)-substituted-aluminum or tri(hydrocarbyl)-boron
compounds are tri((C.sub.1-C.sub.10)alkyl)aluminum or
tri((C.sub.6-C.sub.18)aryl)boron compounds and halogenated
(including perhalogenated) derivatives thereof. In some other
embodiments, exemplary Group 13 metal compounds are
tris(fluoro-substituted phenyl)boranes, in other embodiments,
tris(pentafluorophenyl)borane. In some embodiments, the activating
co-catalyst is a tris((C.sub.1-C.sub.20)hydrocarbyl) borate (e.g.,
trityl tetrafluoroborate) or a
tri((C.sub.1-C.sub.20)hydrocarbyl)ammonium
tetra((C.sub.1-C.sub.20)hydrocarbyl)borane (e.g.,
bis(octadecyl)methylammonium tetrakis(pentafluorophenyl)borane). As
used herein, the term "ammonium" means a nitrogen cation that is a
((C.sub.1-C.sub.20)hydrocarbyl).sub.4N.sup.+, a
((C.sub.1-C.sub.20)hydrocarbyl).sub.3N(H).sup.+, a
((C.sub.1-C.sub.20)hydrocarbyl).sub.2N(H).sub.2.sup.+,
(C.sub.1-C.sub.20)hydrocarbylN(H).sub.3.sup.+, or N(H).sub.4.sup.+,
wherein each (C.sub.1-C.sub.20)hydrocarbyl may be the same or
different.
Exemplary combinations of neutral Lewis acid activating
co-catalysts include mixtures comprising a combination of a
tri((C.sub.1-C.sub.4)alkyl)aluminum and a halogenated
tri((C.sub.6-C.sub.18)aryl)boron compound, especially a
tris(pentafluorophenyl)borane. Other exemplary embodiments are
combinations of such neutral Lewis acid mixtures with a polymeric
or oligomeric alumoxane, and combinations of a single neutral Lewis
acid, especially tris(pentafluorophenyl)borane with a polymeric or
oligomeric alumoxane. Exemplary embodiments ratios of numbers of
moles of (metal-ligand complex):(tris(pentafluoro-phenylborane):
(alumoxane) [e.g., (Group 4 metal-ligand
complex):(tris(pentafluoro-phenylborane):(alumoxane)] are from
1:1:1 to 1:10:30, other exemplary embodiments are from 1:1:1.5 to
1:5:10.
Many activating co-catalysts and activating techniques have been
previously taught, with respect to different metal-ligand
complexes, in the following USPNs: U.S. Pat. No. 5,064,802; U.S.
Pat. No. 5,153,157; U.S. Pat. No. 5,296,433; U.S. Pat. No.
5,321,106; U.S. Pat. No. 5,350,723; U.S. Pat. No. 5,425,872; U.S.
Pat. No. 5,625,087; U.S. Pat. No. 5,721,185; U.S. Pat. No.
5,783,512; U.S. Pat. No. 5,883,204; U.S. Pat. No. 5,919,983; U.S.
Pat. No. 6,696,379; and U.S. Pat. No. 7,163,907. Examples of
suitable hydrocarbyloxides are disclosed in U.S. Pat. No.
5,296,433. Examples of suitable Bronsted acid salts for addition
polymerization catalysts are disclosed in U.S. Pat. No. 5,064,802;
U.S. Pat. No. 5,919,983; U.S. Pat. No. 5,783,512. Examples of
suitable salts of a cationic oxidizing agent and a
non-coordinating, compatible anion, as activating co-catalysts for
addition polymerization catalysts, are disclosed in U.S. Pat. No.
5,321,106. Examples of suitable carbenium salts as activating
co-catalysts for addition polymerization catalysts are disclosed in
U.S. Pat. No. 5,350,723. Examples of suitable silylium salts, as
activating co-catalysts for addition polymerization catalysts, are
disclosed in U.S. Pat. No. 5,625,087. Examples of suitable
complexes of alcohols, mercaptans, silanols, and oximes with
tris(pentafluorophenyl)borane are disclosed in U.S. Pat. No.
5,296,433. Some of these catalysts are also described in a portion
of U.S. Pat. No. 6,515,155 B1, beginning at column 50, at line 39,
and going through column 56, at line 55, only the portion of which
is incorporated by reference herein.
In some embodiments, the above described catalyst systems can be
activated to form an active catalyst composition by combination
with one or more cocatalyst, such as a cation forming cocatalyst, a
strong Lewis acid, or a combination thereof. Suitable cocatalysts
for use include polymeric or oligomeric aluminoxanes, especially
methyl aluminoxane, as well as inert, compatible, noncoordinating,
ion forming compounds. Exemplary suitable cocatalysts include, but
are not limited to, modified methyl aluminoxane (MMAO),
bis(hydrogenated tallow alkyl)methyl,
tetrakis(pentafluorophenyl)borate(1-) amine, triethyl aluminum
(TEA), and any combinations thereof.
In some embodiments, one or more of the foregoing activating
co-catalysts are used in combination with each other. In one
embodiment, a combination of a mixture of a
tri((C.sub.1-C.sub.4)hydrocarbyl)aluminum,
tri((C.sub.1-C.sub.4)hydrocarbyl)borane, or an ammonium borate with
an oligomeric or polymeric alumoxane compound, can be used.
Additives, Additional Polymers and Applications
An inventive composition may comprise one or more additives.
Additives include, but are not limited to, antistatic agents, color
enhancers, dyes, lubricants, fillers (for example, TiO.sub.2 or
CaCO.sub.3), opacifiers, nucleators, processing aids, pigments,
primary anti-oxidants, secondary anti-oxidants, UV stabilizers,
anti-blocks, slip agents, tackifiers, fire retardants,
anti-microbial agents, odor reducer agents, anti-fungal agents, and
combinations thereof. An inventive composition may comprise from
about 0.001 to about 10 percent by the combined weight of such
additives, based on the weight of the composition including such
additives.
An inventive composition may further comprise one or more other
polymers. For example one or more other ethylene-based polymers
(such polymers differ in one or more properties from the
ethylene-based polymer of the first composition and the second
ethylene-based polymer; i.e., density, melt index, comonomer, Mn,
Mw, and/or MWD), or one or more propylene-based polymers, or
combinations thereof. Such compositions may be blended via any
method, known to a person of ordinary skill in the art, including,
but not limited to, dry blending, and melt blending via any
suitable equipment, for example, an extruder.
The invention provides for an article comprising at least one
component formed from an inventive composition. Articles includes,
but are not limited to, film, sheets, coatings, and multilayer
structures. Multilayer structures typically comprise one or more
film layers or sheets comprising an inventive composition. The
multilayer structure may further comprise one or more layers
comprising one or more polyamides, one or more polyesters, one or
more olefin-based polymers, and combinations thereof.
Other articles include, but are not limited to, consumer and
industrial packaging applications, such as construction film, heavy
duty shipping sacks, protective film, waste management, and
agricultural films, which require a film with high dart, puncture
and/or tear resistance properties.
In one embodiment, the inventive compositions according to the
present invention are characterized by one or more of the
followings: (a) having a Dart impact A of at least 400 g, measured
according to ASTM D1709 (Method A), when said composition is formed
into a monolayer blown film having a thickness of 1 mil; and/or (b)
having a normalized machine direction Elmendorf tear of at least
250 g/mil, measured according to ASTM D1922, when said polyolefin
composition is formed into a monolayer blown film having a
thickness of 1 mil.
In one embodiment, an inventive composition further comprises from
5 to 20 percent by weight of low density polyethylene (LDPE). In a
further embodiment, the composition has a Dart Impact A greater
than 275 g, preferably greater than 300 g, measured according to
ASTM D1709, when said composition is formed into a monolayer blown
film having a thickness of 1 mil.
DEFINITIONS
Unless stated to the contrary, implicit from the context, or
customary in the art, all parts and percents are based on weight,
and all test methods are current as of the filing date of this
disclosure.
The term "composition," as used herein, includes material(s) which
comprise the composition, as well as reaction products and
decomposition products formed from the materials of the
composition.
The term "comprising," and derivatives thereof, is not intended to
exclude the presence of any additional component, step or
procedure, whether or not the same is disclosed herein. In order to
avoid any doubt, all compositions claimed, herein, through use of
the term "comprising" may include any additional additive,
adjuvant, or compound, whether polymeric or otherwise, unless
stated to the contrary. In contrast, the term, "consisting
essentially of" excludes from the scope of any succeeding
recitation any other component, step or procedure, excepting those
that are not essential to operability. The term "consisting of"
excludes any component, step or procedure not specifically
delineated or listed.
The term "polymer," as used herein, refers to a polymeric compound
prepared by polymerizing monomers, whether of the same or a
different type. The generic term polymer thus embraces the term
homopolymer (employed to refer to polymers prepared from only one
type of monomer, with the understanding that trace amounts of
impurities can be incorporated into the polymer structure), and the
term interpolymer as defined hereinafter. Trace amounts of
impurities may be incorporated into and/or within the polymer.
The term "interpolymer," as used herein, refers to a polymer
prepared by the polymerization of at least two different types of
monomers. The generic term interpolymer thus includes copolymers
(employed to refer to polymers prepared from two different types of
monomers), and polymers prepared from more than two different types
of monomers.
The term, "olefin-based polymer," as used herein, refers to a
polymer that comprises, in polymerized form, a majority amount of
olefin monomer, for example ethylene or propylene (based on the
weight of the polymer), and optionally may comprise at least one
polymerized comonomer.
The term, "ethylene-based polymer," as used herein, refers to a
polymer that comprises a majority amount of polymerized ethylene
monomer (based on the total weight of the polymer), and optionally
may comprise at least one polymerized comonomer.
The term, "ethylene/.alpha.-olefin interpolymer," as used herein,
refers to an interpolymer that comprises, in polymerized form, a
majority amount of ethylene monomer (based on the weight of the
interpolymer), and at least one .alpha.-olefin.
The term, "ethylene/.alpha.-olefin copolymer," as used herein,
refers to a copolymer that comprises, in polymerized form, a
majority amount of ethylene monomer (based on the weight of the
copolymer), and an .alpha.-olefin, as the only two monomer
types.
The term "propylene-based polymer," as used herein, refers to a
polymer that comprises, in polymerized form, a majority amount of
propylene monomer (based on the total weight of the polymer) and
optionally may comprise at least one polymerized comonomer.
Test Methods
Melt Index
Melt indices I.sub.2 (or I2) and I.sub.10 (or I10) were measured in
accordance to ASTM D-1238 (method B) at 190.degree. C. and at 2.16
kg and 10 kg load, respectively. Their values are reported in g/10
min.
Density
Samples for density measurement were prepared according to ASTM
D4703. Measurements were made, according to ASTM D792, Method B,
within one hour of sample pressing.
Dynamic Shear Rheology
Each sample was compression-molded into "3 mm thick.times.25 mm
diameter" circular plaque, at 177.degree. C., for five minutes,
under 10 MPa pressure, in air. The sample was then taken out of the
press and placed on a counter top to cool.
Constant temperature, frequency sweep measurements were performed
on an ARES strain controlled rheometer (TA Instruments), equipped
with 25 mm parallel plates, under a nitrogen purge. For each
measurement, the rheometer was thermally equilibrated, for at least
30 minutes, prior to zeroing the gap. The sample disk was placed on
the plate, and allowed to melt for five minutes at 190.degree. C.
The plates were then closed to 2 mm, the sample trimmed, and then
the test was started. The method had an additional five minute
delay built in, to allow for temperature equilibrium. The
experiments were performed at 190.degree. C., over a frequency
range from 0.1 to 100 rad/s, at five points per decade interval.
The strain amplitude was constant at 10%. The stress response was
analyzed in terms of amplitude and phase, from which the storage
modulus (G'), loss modulus (G''), complex modulus (G*), dynamic
viscosity (.eta.* or Eta*), and tan .delta. (or tan delta) were
calculated.
Melt Strength
Melt strength measurements were conducted on a Gottfert Rheotens
71.97 (Goettfert Inc.; Rock Hill, S.C.) attached to a Gottfert
Rheotester 2000 capillary rheometer. A polymer melt was extruded
through a capillary die with a flat entrance angle (180 degrees),
with a capillary diameter of 2.0 mm, and an aspect ratio (capillary
length/capillary diameter) of 15.
After equilibrating the samples at 190.degree. C., for 10 minutes,
the piston was run at a constant piston speed of 0.265 mm/second.
The standard test temperature was 190.degree. C. The sample (about
20 grams) was drawn uniaxially to a set of accelerating nips,
located 100 mm below the die, with an acceleration of 2.4
mm/second.sup.2. The tensile force was recorded, as a function of
the take-up speed of the nip rolls. Melt strength was reported as
the plateau force (cN) before the strand broke. The following
conditions were used, in the melt strength measurements: plunger
speed=0.265 mm/second; wheel acceleration=2.4 mm/s.sup.2; capillary
diameter=2.0 mm; capillary length=30 mm; and barrel diameter=12
mm.
Conventional Gel Permeation Chromatography (Conv. GPC)
A GPC-IR high temperature chromatographic system from PolymerChar
(Valencia, Spain), was equipped with a Precision Detectors
(Amherst, Mass.), 2-angle laser light scattering detector Model
2040, an IR5 infra-red detector and a 4-capillary viscometer, both
from PolymerChar. Data collection was performed using PolymerChar
Instrument Control software and data collection interface. The
system was equipped with an on-line, solvent degas device and
pumping system from Agilent Technologies (Santa Clara, Calif.).
Injection temperature was controlled at 150 degrees Celsius. The
columns used, were three, 10-micron "Mixed-B" columns from Polymer
Laboratories (Shropshire, UK). The solvent used was
1,2,4-trichlorobenzene. The samples were prepared at a
concentration of "0.1 grams of polymer in 50 milliliters of
solvent." The chromatographic solvent and the sample preparation
solvent each contained "200 ppm of butylated hydroxytoluene (BHT)."
Both solvent sources were nitrogen sparged. Ethylene-based polymer
samples were stirred gently at 160 degrees Celsius for three hours.
The injection volume was "200 microliters,` and the flow rate was
"1 milliliters/minute." The GPC column set was calibrated by
running 21 "narrow molecular weight distribution" polystyrene
standards. The molecular weight (MW) of the standards ranges from
580 to 8,400,000 g/mole, and the standards were contained in six
"cocktail" mixtures. Each standard mixture had at least a decade of
separation between individual molecular weights. The standard
mixtures were purchased from Polymer Laboratories. The polystyrene
standards were prepared at "0.025 g in 50 mL of solvent" for
molecular weights equal to, or greater than, 1,000,000 g/mole, and
at "0.050 g in 50 mL of solvent" for molecular weights less than
1,000,000 g/mole.
The polystyrene standards were dissolved at 80.degree. C., with
gentle agitation, for 30 minutes. The narrow standards mixtures
were run first, and in order of decreasing "highest molecular
weight component," to minimize degradation. The polystyrene
standard peak molecular weights were converted to polyethylene
molecular weight using Equation 1 (as described in Williams and
Ward, J. Polym. Sci., Polym. Letters, 6, 621 (1968)):
Mpolyethylene=A.times.(Mpolystyrene).sup.B (Eqn. 1), where M is the
molecular weight, A is equal to 0.4316 and B is equal to 1.0.
Number-average molecular weight (Mn(conv gpc)), weight average
molecular weight (Mw-cony gpc), and z-average molecular weight
(Mz(conv gpc)) were calculated according to Equations 2-4
below.
.function..times..times..times..times..times..times..times..times..times.-
.times..times..times..times..times..times..times..times..function..times..-
times..times..times..times..times..times..times..times..times..times..time-
s..times..times..times..times..times..function..times..times..times..times-
..times..times..times..times..times..times..times..times..times..times..ti-
mes..times..times. ##EQU00001##
In Equations 2-4, the RV is column retention volume
(linearly-spaced), collected at "1 point per second," the IR is the
baseline-subtracted IR detector signal, in Volts, from the IR5
measurement channel of the GPC instrument, and M.sub.PE is the
polyethylene-equivalent MW determined from Equation 1. Data
calculation were performed using "GPC One software (version
2.013H)" from PolymerChar.
Creep Zero Shear Viscosity Measurement Method
Zero-shear viscosities were obtained via creep tests, which were
conducted on an AR-G2 stress controlled rheometer (TA Instruments;
New Castle, Del.), using "25-mm-diameter" parallel plates, at
190.degree. C. The rheometer oven was set to test temperature for
at least 30 minutes, prior to zeroing the fixtures. At the testing
temperature, a compression molded sample disk was inserted between
the plates, and allowed to come to equilibrium for five minutes.
The upper plate was then lowered down to 50 .mu.m (instrument
setting) above the desired testing gap (1.5 mm). Any superfluous
material was trimmed off, and the upper plate was lowered to the
desired gap. Measurements were done under nitrogen purging, at a
flow rate of 5 L/min. The default creep time was set for two hours.
Each sample was compression-molded into a "2 mm thick.times.25 mm
diameter" circular plaque, at 177.degree. C., for five minutes,
under 10 MPa pressure, in air. The sample was then taken out of the
press and placed on a counter top to cool.
A constant low shear stress of 20 Pa was applied for all of the
samples, to ensure that the steady state shear rate was low enough
to be in the Newtonian region. The resulting steady state shear
rates were in the range from 10.sup.-3 to 10.sup.-4 s.sup.-1 for
the samples in this study. Steady state was determined by taking a
linear regression for all the data, in the last 10% time window of
the plot of "log (J(t)) vs. log(t)," where J(t) was creep
compliance and t was creep time. If the slope of the linear
regression was greater than 0.97, steady state was considered to be
reached, then the creep test was stopped. In all cases in this
study, the slope meets the criterion within one hour. The steady
state shear rate was determined from the slope of the linear
regression of all of the data points, in the last 10% time window
of the plot of ".epsilon. vs. t," where .epsilon. was strain. The
zero-shear viscosity was determined from the ratio of the applied
stress to the steady state shear rate.
In order to determine if the sample was degraded during the creep
test, a small amplitude oscillatory shear test was conducted
before, and after, the creep test, on the same specimen from 0.1 to
100 rad/s. The complex viscosity values of the two tests were
compared. If the difference of the viscosity values, at 0.1 rad/s,
was greater than 5%, the sample was considered to have degraded
during the creep test, and the result was discarded.
Zero-Shear Viscosity Ratio (ZSVR) is defined as the ratio of the
zero-shear viscosity (ZSV) of the branched polyethylene material to
the ZSV of a linear polyethylene material (see ANTEC proceeding
below) at the equivalent weight average molecular weight (Mw(conv
gpc)), according to the following Equation 5:
.eta..times..eta..times..eta..times..times..function..times.
##EQU00002##
The ZSV value was obtained from creep test, at 190.degree. C., via
the method described above. The Mw(conv gpc) value was determined
by the conventional GPC method (Equation 3), as discussed above.
The correlation between ZSV of linear polyethylene and its Mw(conv
gpc) was established based on a series of linear polyethylene
reference materials. A description for the ZSV-Mw relationship can
be found in the ANTEC proceeding: Karjala et al., Detection of Low
Levels of Long-chain Branching in Polyolefins, Annual Technical
Conference--Society of Plastics Engineers (2008), 66th 887-891.
.sup.1H NMR Method
A stock solution (3.26 g) was added to "0.133 g of the polymer
sample" in 10 mm NMR tube. The stock solution was a mixture of
tetrachloroethane-d.sub.2 (TCE) and perchloroethylene (50:50, w:w)
with 0.001M Cr.sup.3+. The solution in the tube was purged with
N.sub.2, for 5 minutes, to reduce the amount of oxygen. The capped
sample tube was left at room temperature, overnight, to swell the
polymer sample. The sample was dissolved at 110.degree. C. with
periodic vortex mixing. The samples were free of the additives that
may contribute to unsaturation, for example, slip agents such as
erucamide. Each .sup.1H NMR analysis was run with a 10 mm
cryoprobe, at 120.degree. C., on Bruker AVANCE 400 MHz
spectrometer.
Two experiments were run to get the unsaturation: the control and
the double presaturation experiments. For the control experiment,
the data was processed with an exponential window function with
LB=1 Hz, and the baseline was corrected from 7 to -2 ppm. The
signal from residual .sup.1H of TCE was set to 100, and the
integral I.sub.total from -0.5 to 3 ppm was used as the signal from
whole polymer in the control experiment. The "number of CH.sub.2
group, NCH.sub.2," in the polymer was calculated as follows in
Equation 1A: NCH.sub.2=I.sub.total/2 (Eqn. 1A).
For the double presaturation experiment, the data was processed
with an exponential window function with LB=1 Hz, and the baseline
was corrected from about 6.6 to 4.5 ppm. The signal from residual
.sup.1H of TCE was set to 100, and the corresponding integrals for
unsaturations (I.sub.vinylene, I.sub.trisubstituted, and
I.sub.vinylidene) were integrated. It is well known to use NMR
spectroscopic methods for determining polyethylene unsaturation,
for example, see Busico, V., et al., Macromolecules, 2005, 38,
6988. The number of unsaturation unit for vinylene, trisubstituted,
vinyl and vinylidene were calculated as follows:
N.sub.vinylene=I.sub.vinylene/2 (Eqn. 2A),
N.sub.trisubstituted=I.sub.trisubstitute (Eqn. 3A),
N.sub.vinyl=I.sub.vinyl/2 (Eqn. 4A),
N.sub.vinylidene=I.sub.vinylidene/2 (Eqn. 5A).
The unsaturation units per 1,000 carbons, all polymer carbons
including backbone carbons and branch carbons, were calculated as
follows: N.sub.vinylene/1,000C=(N.sub.vinylene/NCH.sub.2)*1,000
(Eqn. 6A),
N.sub.trisubstituted/1,000C=(N.sub.trisubstituted/NCH.sub.2)*1,000
(Eqn. 7A), N.sub.vinyl/1,000C=(N.sub.vinyl/NCH.sub.2)*1,000 (Eqn.
8A), N.sub.vinylidene/1,000C=(N.sub.vinylidene/NCH.sub.2)*1,000
(Eqn. 9A),
The chemical shift reference was set at 6.0 ppm for the .sup.1H
signal from residual proton from TCE-d2. The control was run with
ZG pulse, NS=4, DS=12, SWH=10,000 Hz, AQ=1.64 s, D1=14 s. The
double presaturation experiment was run with a modified pulse
sequence, with O1P=1.354 ppm, O2P=0.960 ppm, PL9=57 db, PL21=70 db,
NS=100, DS=4, SWH=10,000 Hz, AQ=1.64 s, D1=1 s (where D1 is the
presaturation time), D13=13 s. Only the vinyl levels were reported
in Table 2 below.
.sup.13C NMR Method
Samples are prepared by adding approximately 3 g of a 50/50 mixture
of tetra-chloroethane-d2/orthodichlorobenzene, containing 0.025 M
Cr(AcAc).sub.3, to a "0.25 g polymer sample" in a 10 mm NMR tube.
Oxygen is removed from the sample by purging the tube headspace
with nitrogen. The samples are then dissolved, and homogenized, by
heating the tube and its contents to 150.degree. C., using a
heating block and heat gun. Each dissolved sample is visually
inspected to ensure homogeneity.
All data are collected using a Bruker 400 MHz spectrometer. The
data is acquired using a 6 second pulse repetition delay, 90-degree
flip angles, and inverse gated decoupling with a sample temperature
of 120.degree. C. All measurements are made on non-spinning samples
in locked mode. Samples are allowed to thermally equilibrate for 7
minutes prior to data acquisition. The 13C NMR chemical shifts were
internally referenced to the EEE triad at 30.0 ppm.
C13 NMR Comonomer Content: It is well known to use NMR
spectroscopic methods for determining polymer composition. ASTM D
5017-96; J. C. Randall et al., in "NMR and Macromolecules" ACS
Symposium series 247; J. C. Randall, Ed., Am. Chem. Soc.,
Washington, D.C., 1984, Ch. 9; and J. C. Randall in "Polymer
Sequence Determination", Academic Press, New York (1977) provide
general methods of polymer analysis by NMR spectroscopy.
Molecular Weighted Comonomer Distribution Index (MWCDI)
A GPC-IR, high temperature chromatographic system from PolymerChar
(Valencia, Spain) was equipped with a Precision Detectors'
(Amherst, Mass.) 2-angle laser light scattering detector Model
2040, and an IR5 infra-red detector (GPC-IR) and a 4-capillary
viscometer, both from PolymerChar. The "15-degree angle" of the
light scattering detector was used for calculation purposes. Data
collection was performed using PolymerChar Instrument Control
software and data collection interface. The system was equipped
with an on-line, solvent degas device and pumping system from
Agilent Technologies (Santa Clara, Calif.).
Injection temperature was controlled at 150 degrees Celsius. The
columns used, were four, 20-micron "Mixed-A" light scattering
columns from Polymer Laboratories (Shropshire, UK). The solvent was
1,2,4-trichlorobenzene. The samples were prepared at a
concentration of "0.1 grams of polymer in 50 milliliters of
solvent." The chromatographic solvent and the sample preparation
solvent each contained "200 ppm of butylated hydroxytoluene (BHT)."
Both solvent sources were nitrogen sparged. Ethylene-based polymer
samples were stirred gently, at 160 degrees Celsius, for three
hours. The injection volume was "200 microliters," and the flow
rate was "1 milliliters/minute."
Calibration of the GPC column set was performed with 21 "narrow
molecular weight distribution" polystyrene standards, with
molecular weights ranging from 580 to 8,400,000 g/mole. These
standards were arranged in six "cocktail" mixtures, with at least a
decade of separation between individual molecular weights. The
standards were purchased from Polymer Laboratories (Shropshire UK).
The polystyrene standards were prepared at "0.025 grams in 50
milliliters of solvent" for molecular weights equal to, or greater
than, 1,000,000 g/mole, and at "0.050 grams in 50 milliliters of
solvent" for molecular weights less than 1,000,000 g/mole. The
polystyrene standards were dissolved at 80 degrees Celsius, with
gentle agitation, for 30 minutes. The narrow standards mixtures
were run first, and in order of decreasing "highest molecular
weight component," to minimize degradation. The polystyrene
standard peak molecular weights were converted to polyethylene
molecular weights using Equation 1B (as described in Williams and
Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)):
Mpolyethylene=A.times.(Mpolystyrene).sup.B (Eqn. 1B), where M is
the molecular weight, A has a value of approximately 0.40 and B is
equal to 1.0. The A value was adjusted between 0.385 and 0.425
(depending upon specific column-set efficiency), such that NBS
1475A (NIST) linear polyethylene weight-average molecular weight
corresponded to 52,000 g/mole, as calculated by Equation 3B,
below:
.function..times..times..times..times..times..times..times..times..times.-
.times..times..times..times..times..times..times..times..times..function..-
times..times..times..times..times..times..times..times..times..times..time-
s..times..times..times..times..times..times..times.
##EQU00003##
In Equations 2B and 3B, RV is column retention volume
(linearly-spaced), collected at "1 point per second." The IR is the
baseline-subtracted IR detector signal, in Volts, from the
measurement channel of the GPC instrument, and the M.sub.PE is the
polyethylene-equivalent MW determined from Equation 1B. Data
calculation were performed using "GPC One software (version
2.013H)" from PolymerChar.
A calibration for the IR5 detector ratios was performed using at
least ten ethylene-based polymer standards (polyethylene
homopolymer and ethylene/octene copolymers; narrow molecular weight
distribution and homogeneous comonomer distribution) of known short
chain branching (SCB) frequency (measured by the .sup.13C NMR
Method, as discussed above), ranging from homopolymer (0 SCB/1000
total C) to approximately 50 SCB/1000 total C, where total
C=carbons in backbone+carbons in branches. Each standard had a
weight-average molecular weight from 36,000 g/mole to 126,000
g/mole, as determined by the GPC-LALS processing method described
above. Each standard had a molecular weight distribution (Mw/Mn)
from 2.0 to 2.5, as determined by the GPC-LALS processing method
described above. Polymer properties for the SCB standards are shown
in Table A.
TABLE-US-00001 TABLE A "SCB" Standards SCB/1000 Wt % Comonomer IR5
Area ratio Total C Mw Mw/Mn 23.1 0.2411 28.9 37,300 2.22 14.0
0.2152 17.5 36,000 2.19 0.0 0.1809 0.0 38,400 2.20 35.9 0.2708 44.9
42,200 2.18 5.4 0.1959 6.8 37,400 2.16 8.6 0.2043 10.8 36,800 2.20
39.2 0.2770 49.0 125,600 2.22 1.1 0.1810 1.4 107,000 2.09 14.3
0.2161 17.9 103,600 2.20 9.4 0.2031 11.8 103,200 2.26
The "IR5 Area Ratio (or "IR5.sub.Methyl Channel
Area/IR5.sub.Measurement Channel Area")" of "the
baseline-subtracted area response of the IR5 methyl channel sensor"
to "the baseline-subtracted area response of IR5 measurement
channel sensor" (standard filters and filter wheel as supplied by
PolymerChar: Part Number IR5_FWM01 included as part of the GPC-IR
instrument) was calculated for each of the "SCB" standards. A
linear fit of the SCB frequency versus the "IR5 Area Ratio" was
constructed in the form of the following Equation 4B: SCB/1000
total C=A.sub.0+[A.sub.1.times.(IR5.sub.Methyl Channel
Area/IR5.sub.Measurement Channel Area)] (Eqn. 4B), where A.sub.0 is
the "SCB/1000 total C" intercept at an "IR5 Area Ratio" of zero,
and A.sub.1 is the slope of the "SCB/1000 total C" versus "IR5 Area
Ratio," and represents the increase in the "SCB/1000 total C" as a
function of "IR5 Area Ratio."
A series of "linear baseline-subtracted chromatographic heights"
for the chromatogram generated by the "IR5 methyl channel sensor"
was established as a function of column elution volume, to generate
a baseline-corrected chromatogram (methyl channel). A series of
"linear baseline-subtracted chromatographic heights" for the
chromatogram generated by the "IR5 measurement channel" was
established as a function of column elution volume, to generate a
base-line-corrected chromatogram (measurement channel).
The "IR5 Height Ratio" of "the baseline-corrected chromatogram
(methyl channel)" to "the baseline-corrected chromatogram
(measurement channel)" was calculated at each column elution volume
index (each equally-spaced index, representing 1 data point per
second at 1 ml/min elution) across the sample integration bounds.
The "IR5 Height Ratio" was multiplied by the coefficient A.sub.1,
and the coefficient A.sub.0 was added to this result, to produce
the predicted SCB frequency of the sample. The result was converted
into mole percent comonomer, as follows in Equation 5B: Mole
Percent Comonomer={SCB.sub.f/[SCB.sub.f+((1000-SCB.sub.f*Length of
comonomer)/2)]}*100 (Eqn. 5B), where "SCB.sub.f" is the "SCB per
1000 total C" and the "Length of comonomer"=8 for octene, 6 for
hexene, and so forth.
Each elution volume index was converted to a molecular weight value
(Mw.sub.i) using the method of Williams and Ward (described above;
Eqn. 1B). The "Mole Percent Comonomer (y axis)" was plotted as a
function of Log(Mw.sub.i), and the slope was calculated between
Mw.sub.i of 15,000 and Mw.sub.i of 150,000 g/mole (end group
corrections on chain ends were omitted for this calculation). An
EXCEL linear regression was used to calculate the slope between,
and including, Mw.sub.i from 15,000 to 150,000 g/mole. This slope
is defined as the molecular weighted comonomer distribution index
(MWCDI=Molecular Weighted Comonomer Distribution Index).
Representative Determination of MWCDI (Inventive First Composition
2)
A plot of the measured "SCB per 1000 total C (=SCB.sub.f)" versus
the observed "IR5 Area Ratio" of the SCB standards was generated
(see FIG. 1), and the intercept (A.sub.0) and slope (A.sub.1) were
determined. Here, A.sub.0=-90.246 SCB/1000 total C; and
A.sub.1=499.32 SCB/1000 total C.
The "IR5 Height Ratio" was determined for Inventive Example 2 (see
integration shown in FIG. 2). This height ratio (IR5 Height Ratio
of Inventive Example 2) was multiplied by the coefficient A.sub.1,
and the coefficient A.sub.0 was added to this result, to produce
the predicted SCB frequency of this example, at each elution volume
index, as described above (A.sub.0=-90.246 SCB/1000 total C; and
A.sub.1=499.32 SCB/1000 total C). The SCB.sub.f was plotted as a
function of polyethylene-equivalent molecular weight, as determined
using Equation 1B, as discussed above. See FIG. 3 (Log Mwi used as
the x-axis).
The SCB.sub.f was converted into "Mole Percent Comonomer" via
Equation 5B. The "Mole Percent Comonomer" was plotted as a function
of polyethylene-equivalent molecular weight, as determined using
Equation 1B, as discussed above. See FIG. 4 (Log Mwi used for the
x-axis). A linear fit was from Mwi of 15,000 g/mole to Mwi of
150,000 g/mole, yielding a slope of "2.27 mole percent
comonomer.times.mole/g." Thus, the MWCDI=2.27. An EXCEL linear
regression was used to calculate the slope between, and including,
Mwi from 15,000 to 150,000 g/mole.
Film Testing Conditions
The following physical properties were measured on the films
produced (see experimental section). 45.degree. Gloss: ASTM D-2457.
Clarity: ASTM: D-1746. ASTM D1003 Total Haze
Samples measured for internal haze and overall (total) haze were
sampled and prepared according to ASTM D1003. Internal haze was
obtained via refractive index matching using mineral oil on both
sides of the films. A Hazeguard Plus (BYK-Gardner USA; Columbia,
Md.) was used for testing. Surface haze was determined as the
difference between total haze and internal haze. The total haze was
reported as the average of five measurements.
ASTM D1922 MD (Machine Direction) and CD (Cross Direction)
Elmendorf Tear Type B
The Elmendorf Tear test determines the average force to propagate
tearing through a specified length of plastic film or non rigid
sheeting, after the tear has been started, using an Elmendorf-type
tearing tester.
After film production from the sample to be tested, the film was
conditioned for at least 40 hours at 23.degree. C. (+/-2.degree.
C.) and 50% R.H (+/-5) as per ASTM standards. Standard testing
conditions were 23.degree. C. (+/-2.degree. C.) and 50% R.H (+/-5)
as per ASTM standards.
The force, in grams, required to propagate tearing across a film or
sheeting specimen was measured, using a precisely calibrated
pendulum device. In the test, acting by gravity, the pendulum swung
through an arc, tearing the specimen from a precut slit. The
specimen was held on one side by the pendulum, and on the other
side by a stationary member. The loss in energy by the pendulum was
indicated by a pointer or by an electronic scale. The scale
indication was a function of the force required to tear the
specimen.
The sample specimen geometry used in the Elmendorf tear test was
the `constant radius geometry,` as specified in ASTM D1922. Testing
is typically carried out on specimens that have been cut from both
the film MD and CD directions. Prior to testing, the film specimen
thickness was measured at the sample center. A total of 15
specimens per film direction were tested, and the average tear
strength and average thickness reported. The average tear strength
was normalized to the average thickness.
ASTM D882 MD and CD, 1% and 2% Secant Modulus
The film MD (Machine Direction) and CD (Cross Direction) secant
modulus was determined per ASTM D882. The reported secant modulus
value was the average of five measurements.
Puncture Strength
The Puncture test determines the resistance of a film to the
penetration of a probe, at a standard low rate, a single test
velocity. The puncture test method is based on ASTM D5748. After
film production, the film was conditioned for at least 40 hours at
23.degree. C. (+/-2.degree. C.) and 50% R.H (+/-5), as per ASTM
standards. Standard testing conditions are 23.degree. C.
(+/-2.degree. C.) and 50% R.H (+/-5) as per ASTM standards.
Puncture was measured on a tensile testing machine. Square
specimens were cut from a sheet, to a size of "6 inches by 6
inches." The specimen was clamped in a "4 inch diameter" circular
specimen holder, and a puncture probe was pushed into the centre of
the clamped film, at a cross head speed of 10 inches/minute. The
internal test method follows ASTM D5748, with one modification. It
deviated from the ASTM D5748 method, in that the probe used, was a
"0.5 inch diameter" polished steel ball on a "0.25 inch" support
rod (rather than the 0.75 inch diameter, pear shaped probe
specified in D5748).
There was a "7.7 inch" maximum travel length to prevent damage to
the test fixture. There was no gauge length; prior to testing, the
probe was as close as possible to, but not touching the specimen. A
single thickness measurement was made in the centre of the
specimen. For each specimen, the maximum force, the force at break,
the penetration distance, and the energy to break were determined.
A total of five specimens were tested to determine an average
puncture value. The puncture probe was cleaned using a "Kim-wipe"
after each specimen.
ASTM D1709 Dart Drop
The film Dart Drop test determines the energy that causes a plastic
film to fail, under specified conditions of impact by a free
falling dart. The test result is the energy, expressed in terms of
the weight of the missile falling from a specified height, which
would result in the failure of 50% of the specimens tested.
After the film was produce, it was conditioned for at least 40
hours at 23.degree. C. (+/-2.degree. C.) and 50% R.H (+/-5), as per
ASTM standards. Standard testing conditions are 23.degree. C.
(+/-2.degree. C.) and 50% R.H (+/-5), as per ASTM standards.
The test result was reported as either by Method A, which uses a
1.5'' diameter dart head and 26'' drop height, or by Method B,
which uses a 2'' diameter dart head and 60'' drop height. The
sample thickness was measured at the sample center, and the sample
then clamped by an annular specimen holder with an inside diameter
of 5 inches. The dart was loaded above the center of the sample,
and released by either a pneumatic or electromagnetic
mechanism.
Testing was carried out according to the `staircase` method. If the
sample failed, a new sample was tested with the weight of the dart
reduced by a known and fixed amount. If the sample did not fail, a
new sample was tested with the weight of the dart increased by a
known amount. After 20 specimens had been tested, the number of
failures was determined. If this number was 10, then the test is
complete. If the number was less than 10, then the testing
continues, until 10 failures had been recorded. If the number was
greater than 10, testing was continued, until the total of
non-failures was 10. The Dart Drop strength was determined from
these data, as per ASTM D1709, and expressed in grams, as either
the Dart Drop impact of Type A or Type B. In some cases, the sample
Dart Drop Impact strength may lie between A and B. In these cases,
it is not possible to obtain a quantitative dart value.
EXPERIMENTAL
The following examples illustrate the present invention, but are
not intended to limit the scope of the invention.
Inventive First Compositions 1, 2 and 3
Inventive first compositions 1, 2 and 3, each contain two
ethylene-octene copolymers. Each composition was prepared, via
solution polymerization, in a dual series loop reactor system
according to U.S. Pat. No. 5,977,251 (see FIG. 2 of this patent),
in the presence of a first catalyst system, as described below, in
the first reactor, and a second catalyst system, as described
below, in the second reactor.
The first catalyst system comprised a
bis((2-oxoyl-3-(dibenzo-1H-pyrrole-1-yl)-5-(methyl)phenyl)-2-phenoxymethy-
l)-methylene-1,2-cyclohexanediylhafnium (IV) dimethyl, represented
by the following formula (CAT 1):
##STR00007##
The molar ratios of the metal of CAT 1, added to the polymerization
reactor, in-situ, to that of Cocat1 (modified methyl aluminoxane),
or Cocat2 (bis(hydrogenated tallow alkyl)methyl,
tetrakis(pentafluorophenyl)borate(1-)amine), are shown in Table
1.
The second catalyst system comprised a Ziegler-Natta type catalyst
(CAT 2). The heterogeneous Ziegler-Natta type catalyst-premix was
prepared substantially according to U.S. Pat. No. 4,612,300, by
sequentially adding to a volume of ISOPAR E, a slurry of anhydrous
magnesium chloride in ISOPAR E, a solution of EtAlCl.sub.2 in
heptane, and a solution of Ti(O-iPr).sub.4 in heptane, to yield a
composition containing a magnesium concentration of 0.20M, and a
ratio of Mg/Al/Ti of 40/12.5/3. An aliquot of this composition was
further diluted with ISOPAR-E, to yield a final concentration of
500 ppm Ti in the slurry. While being fed to, and prior to entry
into, the polymerization reactor, the catalyst premix was contacted
with a dilute solution of Et.sub.3Al, in the molar Al to Ti ratio
specified in Table 1, to give the active catalyst.
The polymerization conditions for the inventive first compositions
1, 2 and 3 are reported in Table 1. As seen in Table 1, Cocat. 1
(modified methyl aluminoxane (MMAO)); and Cocat. 2
(bis(hydrogenated tallow alkyl)methyl,
tetrakis(pentafluorophenyl)borate(1-)amine) were each used as a
cocatalyst for CAT 1. Additional properties of the inventive
compositions 1, 2 and 3 were measured, and are reported in Table 2.
The GPC MWD profiles, and corresponding comonomer distribution
overlays, are shown in FIGS. 5-7. Each polymer composition was
stabilized with minor (ppm) amounts of stabilizers.
Comparative First Compositions A and B
Comparative compositions A and B, each contain two ethylene-octene
copolymers, and each was prepared, via solution polymerization, in
a dual loop reactor system, in the presence of a first catalyst
system, as described below, in the first reactor, and a second
catalyst system, as described below, in the second reactor. The
first catalyst system comprised titanium,
[N-(1,1-dimethylethyl)-1,1-dimethyl-1-[(1,2,3,3a,8a-.eta.)-1,5,6,7-tetrah-
ydro-2-methyl-s-indacen-1-yl]silanaminato(2-)-.kappa.N][(1,2,3,4-.eta.)-1,-
3-pentadiene]-(CAT 3, a constrained geometry catalyst). The second
catalyst system comprised the Ziegler-Natta premix (CAT 2), as
discussed above.
The polymerization conditions for comparative compositions A and B
are reported in Table 1. As seen in Table 1, Cocat. 1 (modified
methyl aluminoxane (MMAO)) and Cocat. 2 (bis(hydrogenated tallow
alkyl)methyl, tetrakis(pentafluorophenyl)borate(1-)amine) were each
used as cocatalyst for CAT 3. Additional properties of the
comparative compositions A and B were measured, and are reported in
Table 2. The GPC MWD profiles, and corresponding comonomer
distribution overlays, are shown in FIGS. 5 and 6. Each polymer
composition was stabilized with minor (ppm) amounts of
stabilizers.
Comparative C (First Composition)
Comparative C is an ethylene-hexene copolymer composition,
commercially available under the commercial designation EXCEED
1018CA from EXXONMOBIL Chemical Company, and having a density of
approximately 0.918 g/cm.sup.3, a melt index (I.sub.2 or I2),
measured at 190.degree. C. and 2.16 kg, of approximately 1.0 g/10
minutes. Additional properties of the comparative example C were
measured, and are reported in Table 2. The GPC MWD profile, and
corresponding comonomer distribution overlay, is shown in FIG.
5.
Comparative D (First Composition)
Comparative D is an ethylene-octene copolymer composition, provided
by The Dow Chemical Company, under the commercial designation ELITE
5230G, and having a density of approximately 0.916 g/cm.sup.3, a
melt index (I.sub.2 or I2), measured at 190.degree. C. and 2.16 kg,
of approximately 4.0 g/10 minutes. Additional properties of the
comparative example D were measured, and are reported in Table 2.
The GPC MWD profile, and corresponding comonomer distribution
overlay, is shown in FIG. 7.
TABLE-US-00002 TABLE 1 Polymerization Conditions (Rx1 = reactor 1;
Rx2 = reactor 2) Sample # Units Inv. First 1 Inv. First 2 Inv.
First 3 Comp. First A Comp. First B Reactor Configuration Dual
Series Dual Series Dual Series Dual Series Dual Series Comonomer
1-octene 1-octene 1-octene 1-octene 1-octene REACTOR FEEDS Rx1
Total Solvent Flow lb/hr 1122 1057 1177 958 1061 Rx1 Fresh Ethylene
Flow lb/hr 181 167 260 176 178 Rx1 Total Ethylene Flow lb/hr 190
175 269 184 187 Rx1 Fresh Comonomer Flow lb/hr 42 29 61 29 28 Rx1
Total Comonomer Flow lb/hr 74 48 118 97 58 Rx1 Feed
Solvent/Ethylene Ratio 6.19 6.32 4.52 5.44 5.96 Ratio Rx1 Hydrogen
Mole Percent mol % 0.55 0.44 1.29 0.04 0.07 Rx1 Hydrogen Feed Flow
SCCM 6827 5017 22848 525 857 Rx2 Total Solvent Flow lb/hr 384 451
421 494 561 Rx2 Fresh Ethylene Flow lb/hr 170 200 152 178 211 Rx2
Total Ethylene Flow lb/hr 173 204 155 182 216 Rx2 Fresh Comonomer
Flow lb/hr 0 0 0 15 0 Rx2 Total Comonomer Flow lb/hr 12 8 22 50 17
Rx2 Hydrogen feed Flow SCCM 298 99 100 2446 3829 Rx2 Feed
Solvent/Ethylene Ratio 2.26 2.25 2.77 2.78 2.65 Ratio Rx2 Hydrogen
Mole Percent mol % 0.03 0.01 0.01 0.21 0.27 REACTION Rx1 Control
Temperature .degree. C. 140 150 143 145 135 Rx1 Ethylene Conversion
% 86.7 90.5 72.7 69.4 77.7 Rx1 FTnIR Exit C2 Conc. g/L 12.1 8.5
31.2 29.5 20.6 Rx1 Viscosity cP 2400 2315 824 891 1318 Rx2 Control
Temperature .degree. C. 195 195 190 190 195 Rx2 Ethylene Conversion
% 87.1 86.0 87.8 89.2 88.8 Rx2 FTnIR Exit C2 Conc g/L 8.3 9.9 8.5
8.6 8.6 Rx2 Viscosity cP 869 876 264 892 848 CATALYST Rx1 Catalyst
CAT 1 CAT 1 CAT 1 CAT 3 CAT 3 Rx1 Catalyst Efficiency g Polymer/g
3,681,068 2,333,579 481,051 2,984,071 2,653,724 catalyst metal Rx1
Cocat. 2 to Catalyst Ratio 1.3 1.8 1.2 1.2 1.5 Metal Molar Ratio
Rx1 Cocat. 1 to Catalyst Ratio 20 100 5 15 25 Metal Molar Ratio Rx2
Catalyst Efficiency g Polymer/g 404,385 469,511 176,500 561,063
390,994 catalyst metal Rx2 Al to Ti Molar Ratio Ratio 4.0 4.0 1.2
4.0 4.0 *solvent = ISOPAR E
TABLE-US-00003 TABLE 2 Properties of Inventive and Comparative
Compositions Comp. Comp. Comp. Comp. Unit Inv. First 1 Inv. First 2
Inv. First 3 First A First B First C First D Density g/cc 0.9174
0.9245 0.9148 0.9162 0.9253 0.9191 0.9158 I.sub.2 g/10 min 0.83
0.87 3.91 0.93 0.80 0.95 4.05 I.sub.10/I.sub.2 7.7 8.0 7.3 8.2 8.4
6.0 7.0 7.0 - 7.1 7.1 6.3 7.0 7.1 7.0 6.3 1.2 .times. log(I2) Mn
g/mol 32,973 33,580 20,244 33,950 34,626 45,645 26,355 (conv. gpc)
Mw 117,553 117,172 78,820 111,621 112,688 109,931 76,118 (conv.
gpc) Mz 270,191 277,755 186,520 258,547 254,301 197,425 155,254
(conv. gpc) Mw/Mn 3.57 3.49 3.89 3.29 3.25 2.41 2.89 (conv. gpc)
Mz/Mw 2.30 2.37 2.37 2.32 2.26 1.80 2.04 (conv. gpc) Eta* (0.1
rad/s) Pa s 9,496 11,231 1,997 10,342 11,929 6,975 2,057 Eta* (1.0
rad/s) Pa s 7,693 8,455 1,920 7,313 7,942 6,472 1,908 Eta* (10
rad/s) Pa s 4,706 4,977 1,527 4,337 4,586 5,071 1,473 Eta* (100
rad/s) Pa s 1,778 1,893 792 1,769 1,873 2,415 834 Eta*0.1/ 5.34
5.93 2.52 5.85 6.37 2.89 2.47 Eta*100 Eta zero Pa s 11,210 13,947
2,142 12,994 15,661 7,748 2,176 Melt Strength cN 3.5 4.0 NM 3.9 4.5
3.0 NM MWCDI 2.64 2.27 1.56 0.65 0.79 -0.06 -0.54 Vinyls Per 1000
134 179 115 157 148 69 56 total Carbons ZSVR 1.53 1.92 1.25 2.13
2.49 1.35 1.45 NM = Not Measured.
Monolayer Blown Films
Monolayer blown films were produced from the inventive compositions
1 and 2 and comparative compositions A, B and C, via an Egan Davis
Standard extruder, equipped with a semi grooved barrel of ID 3.5
inch; 30/1 L/D ratio; a barrier screw, and an Alpine air ring. The
extrusion line had an "8 inch die" with internal bubble cooling.
The extrusion line also had a film thickness gauge scanner. The
film fabrication conditions were as follows: film thickness
maintained at 1 mil (0.001 in or 0.0254 mm); blow up ratio (BUR)
2.5; die gap 90 mil; and frost line height (FLH) 30 inch, at a
output rate of approximately "10 lbs per inch" of circumference of
the die, and an approximately 410 degree Fahrenheit polymer melt
temperature. Film properties are reported in Table 3.
Inventive compositions 1 and 2 and Comparative compositions A, B
and C were further dry blended with a low density polyethylene
(LDPE) at 80:20 weight ratio (Expt. First Composition: LDPE), and
the respective monolayer blown films were produced via an Egan
Davis Standard extruder, equipped with a semi grooved barrel of ID
3.5 inch; 30/1 L/D ratio; a barrier screw, and an Alpine air ring.
The extrusion line had an "8 inch die" with internal bubble
cooling. The extrusion line also had a film thickness gauge
scanner. The film fabrication conditions were as follows: film
thickness maintained at 1 mil (0.001 in or 0.0254 mm); blow up
ratio (BUR) 2.5; die gap 90 mil; and frost line height (FLH) 30
inch, at a output rate of approximately 10 lbs per inch of
circumference of the die, and an approximately 410 degree
Fahrenheit polymer melt temperature. The LDPE (AGILITY 1021 from
The Dow Chemical Company) had melt index I.sub.2 of 2 g/10 minutes,
and density of 0.919 g/cm.sup.3. Film properties are reported in
Table 3.
Monolayer Cast Films
Monolayer cast films of inventive composition 3 and comparative
composition D were fabricated on a 5 layer, Egan Davis Standard
coextrusion cast film line. Film thickness was maintained at 0.8
mil (0.0008 in or 0.02 mm). The cast line consisted of three 21/2''
and two 2'' "30:1 L/D Egan Davis Standard MAC extruders," which are
air cooled. All extruders had moderate work DSB (Davis Standard
Barrier) type screws. A CMR 2000 microprocessor monitored and
controlled the operations. The extrusion process was monitored by
pressure transducers, located before, and after, the breaker plate,
as well as by four heater zones on each barrel, one each at the
adapter and the block and two zones on the die. The microprocessor
also tracked the extruder RPM, % FLA, HP, rate, line speed, % draw,
primary and secondary chill roll temperatures, gauge deviation,
layer ratio, rate/RPM, and melt temperature for each extruder.
Equipment specifications included a Cloeren 5 layer, dual plane
feed block, and a Cloeren 36'' Epich II autogage 5.1 die. The
primary chill roll had a matte finish, and was 40'' O.D..times.40''
long, with a 30-40 RMS surface finish for improved release
characteristics. The secondary chill roll is 20'' O.D..times.40''
long, with a 2-4 RMS surface for improved web tracking. Both the
primary and secondary chill rolls had chilled water circulating
through them, to provide quenching. There was an NDC Beta gauge
sensor for gauge thickness and automatic gauge control, if needed.
Rate was measured by five Barron weigh hoppers, with load cells on
each hopper for gravimetric control. Samples were finished on the
two position, single turret Horizon winder, on 3'' I.D. cores, with
center wind automatic roll changeover and slitter station. The
maximum throughput rate for the line was "600 pounds per hour," and
maximum line speed was "900 feet per minute." Film properties are
shown in Table 4.
Monolayer cast films for inventive composition 3 and comparative
composition D were fabricated based on the following conditions:
Melt Temperature=530.degree. F. Temperature Profile (B1 300.degree.
F.:B2 475.degree. F., B3-5 525.degree. F., Screen 525.degree. F.,
Adaptor 525.degree. F., Die all zones 525.degree. F.) Line
speed=470 ft/min Through put rate=370-400 lb/hr Chill roll
temperature=70.degree. F. Cast roll temperature=70.degree. F. Air
knife=7.4'' H.sub.2O Vacuum box=OFF Die gap=20-25 mil
TABLE-US-00004 TABLE 3 Blown Film Properties Inv. 1 Inv. 2 Comp. A
Comp. B Comp. C 100% Expt. First Composition Dart Drop Impact g
1363 553 583 238 880 (Method-A) Normalized tear (MD) g/mil 280 251
314 269 277 Normalized tear (CD) g/mil 526 611 593 666 386 Gloss -
45 degree % 39 35 52 37 44 Haze - total % 19.4 18.7 13.2 21.0 12.7
Puncture Strength ft * lbf/in 3 362 310 419 252 416 Secant Modulus
- MD at psi 35,612 45,023 30,013 51,238 31,178 1% strain Secant
Modulus - MD at psi 32,243 39,572 26,818 43,100 26,890 2% strain
80% Expt. First Composition + 20% LDPE Dart Drop Impact g 494 176
200 143 241 (Method-A) Normalized tear (MD) g/mil 135 115 141 116
115 Normalized tear (CD) g/mil 739 821 692 759 645 Gloss - 45
degree % 76 70 70 62 82 Haze - total % 4.7 6.0 5.5 7.5 3.1 Puncture
Strength ft * lbf/in 3 246 193 274 168 298 Secant Modulus - MD at
psi 45,544 53,234 34,564 45,254 38,927 1% strain Secant Modulus -
MD at psi 38,999 45,301 30,772 41,253 34,383 2% strain
TABLE-US-00005 TABLE 4 Cast Film Properties Unit Inv. 3 Comp. D
Dart Drop Impact (Method-A) g 463 211 Normalized tear (MD) g/mil
375 351 Normalized tear (CD) g/mil 557 600 Clarity % 99.5 99.6
Puncture Strength ft*lbf/in{circumflex over ( )}3 225 352 Secant
Modulus - MD at 1% strain psi 14,676 14,803 Secant Modulus - MD at
2% strain psi 13,232 13,732 Secant Modulus - CD at 1% strain psi
14,479 15,084 Secant Modulus - CD at 2% strain psi 13,654
13,829
It has been discovered, that for blown films, within the density
range from 0.916 to 0.919 g/cc, inventive first composition 1
showed significantly higher toughness (as indicated by dart drop
impact values) than comparative compositions A and C. Within the
density range from 0.924 to 0.926 g/cc, inventive first composition
2 also showed significantly higher toughness (as indicated by dart
drop impact values) than comparative composition B. It has also
been discovered, that, for the cast films, inventive example 3
showed significantly higher toughness (as indicated by dart drop
impact values) than comparative composition D. It is believed that
the improved film toughness from the inventive compositions is a
result of their high MWCDI values. From a molecular structure
standpoint, a high MWCDI value indicates comonomers are more
favorably incorporated (a higher incorporation of comonomer and a
better distribution of comonomer) in the high molecular weight
polymer molecules, rather than in the low molecular weight polymer
molecules. The inventive compositions also have low LCB, as
indicated by low ZSVR, as compared to conventional polymers. As a
result, the polymer contains more tie chains, and therefore,
provides better film toughness. The inventive compositions also
have significantly high I10/I2 values, indicating good
processibility of these compositions.
* * * * *